Lip prints.

Investigators often gain evidence through the use of odontology, anthropometry (measuring the body), fingerprints, and other techniques that determine gender, approximate age, height, and blood grouping. Today, however, investigators can also rely on lip prints to identify possible suspects or to support evidence gained in specific investigations.

As with fingerprints, experts can lift lip prints from objects found at crime scenes and compare these prints to a suspect's lip pattern. Lip prints can also support dental record comparisons in homicide cases where dismemberment makes identification difficult or when victims do not have teeth or readily available dental records.

Background

In 1970, Japanese researchers reported their findings on a lip print study. During the study, researchers examined the lip prints of 1,364 individuals, ranging from 3 to 60 years of age. They prepared the prints by using both photographs and a fingerprint system.(1) They then classified the prints according to their distinguishing features.

In 1991, the author conducted a lip print study, comparing the lip prints of 150 individuals, ranging in age from 4 to 85 years of age. This study included both genders, as well as five pairs of identical twins, and applied the same methods of classification and recording as those in the previous study.

However, in the second study, researchers transferred lip prints by using lip rouge rather than a fingerprint system. In addition, two findings from the first study were not considered in the 1991 study: Lip inflamation can alter lip prints, but the prints return to normal when the condition is relieved; and lip prints do not change with age.(2)

Although methods for obtaining prints differed somewhat in the two studies, the results were the same. Findings indicated that:

* Every individual has unique lip prints--no two were identical in any case

* Heredity plays some role in lip pattern development (Similarities were found between parents and children.)

* Unique features are distinguishable (Although parents and their children have similar groove traits, the prints are not identical, even in the case of identical twins.)

Classification Method

When classifying lip prints, experts divide distinguishing labial wrinkles and grooves of the lips into two categories--simple and compound. Simple wrinkles and grooves are subdivided into four groups: Those with a straight line, a curved line, an angled line, or a sine-shaped curve. Compound wrinkles and grooves are classified into bifurcated, trifurcated, or anomalous.(3)

Six types of distinguishing features exist in lip prints:

* Type I--clear-cut lines or grooves that run vertically across the lip

* Type I/--straight grooves that disappear half-way into the lip instead of covering the entire breadth of the lip

* Type II--grooves that fork

* Type III--grooves that intersect

* Type IV--grooves that are reticulate (netlike)

* Type V--grooves that do not fall into any of the above categories and cannot be differentiated morphologically.(4)

Experts cannot categorize a lip print as a single type, since combinations of groove types exist in nearly all cases. Instead, they designate a single lip print type based on the prominance of groove type.

Recording Method

Once experts classify lip patterns, they record them by noting the combinations of groove types found in each print. A horizontal line divides the upper lip from the lower lip, and a median line partitions the right and left sides. Experts then record the combinations of groove patterns for each quadrant of the print.(5)

Conclusion

Findings from lip print studies make a strong case for their use in solving crimes. Although not useful for identification under conditions where only skeletal structures remain, intacts lips provide prints that can provide valuable legal evidence.

Many law enforcement agencies remain unaware of the usefulness of lip prints when attempting to identify suspects, and as a result, important evidence is lost. With increasing number of unsolved crimes, the criminal justice community must look seriously at any new method that provides the evidence necessary to gain convictions. Law enforcement personnel should begin to consider lip print analysis as yet another tool to use for solving crimes.

Endnotes

1 K. Suzuki and Y. Tsuchihashi, "Personal Identification by Means of Lip Prints," Journal of Forensic Medicine, 1970, 52-57.

2 Y. Tsuchihashi, "Studies on Personal Identification by Means of Lip Prints," Forensic Science, 1974, 233-248.

3 Ibid.

4 Ibid.

5 Ibid.

Dr. Schnuth is an associate professor at Old Dominion University in Norfolk, Virginia.